Back light unit and liquid crystal display apparatus

ABSTRACT

A back light unit includes a lamp, a lamp house where the lamp is housed, a diffusion plate provided parallel to a main surface of the lamp house, a display part receiving light irradiated from the lamp and displaying, a frame member that has a structure in which the diffusion plate and the display part can be housed inside of the frame member and that detachably connects to the lamp house, and a shield member connected in a range from the diffusion plate to the frame member so that a space between the diffusion plate and the frame member is shielded.

This is a divisional of application Ser. No. 10/100,423, filed Mar. 18,2002, and issued as U.S. Pat. No. 7,283,118 on Oct. 16, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to back light units and liquidcrystal displays, and more particularly, to a back light unit and aliquid crystal display having a structure by which a foreign body isprevented from invading the space between the back light unit and aliquid crystal panel.

2. Description of the Related Art

There are several types of display apparatuses, such as a liquid crystaldisplay or a cathode ray tube (CRT).

Since the liquid crystal display apparatus has several good points suchas low consumption of electric power and a small thickness, marketing ofthe liquid crystal display apparatus has been expanding. Therefore, theliquid crystal display apparatus needs to have various properties morethan the CRT.

The most important property required of the liquid crystal displayapparatus is to have high luminance. Particularly, a liquid crystaldisplay is required to have several times the luminance of the relatedart liquid crystal displays, without increasing manufacturing cost ofthe liquid crystal display apparatus.

As a means for realizing the high luminance of the liquid crystaldisplay, up to now, using fluorescent tubes, namely lamps, as a lightsource, the electrical power provided to the individual fluorescenttubes has been increased, or the number of fluorescent tubes has beenincreased.

However, if high luminance of each of the fluorescent tubes is provided,other members in the liquid crystal display apparatus are thermallyinfluenced by the heat generated by the fluorescent tubes. In addition,if the number of the fluorescent tubes is increased, other members inthe liquid crystal display apparatus are thermally influenced andminiaturization of the liquid crystal display apparatus is obstructed.Thus, other means are necessary for realizing high luminance of theliquid crystal display apparatus.

Meanwhile, there are two types of back light units used for the liquidcrystal display apparatus, an edge light type and a direct under type.

FIG. 1 is a schematic illustration of a structure of a related art edgelight type back light unit.

Referring to FIG. 1, the edge light type back light unit 1 a includesplural cold cathode fluorescent tubes 3 a. Each of the cold cathodefluorescent tubes 3 a faces two side surfaces of the light guide plate2. Reflectors 4 a are provided as the reflectors 4 a covercircumferences of the cold cathode fluorescent tubes 3 a except anirradiation direction of the cold cathode fluorescent tubes 3 a. Areflection sheet 5 is provided at a lower surface (back surface) side ofthe light guide plate 2. A diffuse reflection pattern 6 is formed on alower surface of the light guide plate 2. The configuration,measurements, and density of the diffuse reflection pattern 6 arearranged appropriately. A diffusion plate (diffusion sheet) 6 a isprovided at an upper surface side of the light guide plate 2. A prismsheet 7 is further arranged on an upper surface of the diffusion plate 6a. A liquid crystal panel not shown in FIG. 1 is arranged at an upperposition of the prism sheet 7 so that the liquid crystal displayapparatus can be obtained.

In the edge light type back light unit 1 a, a light radiated from thecold cathode fluorescent tubes 3 a irradiates into the light guide plate2. The light irradiated into the light guide plate 2 is changed to alight having a uniform luminance in a radiation surface of the lightguide plate 2 by the diffuse reflection pattern 6. The light radiatedfrom the light guide plate 2 permeates through the diffusion plate 6 aand the prism sheet 7 so that a moving direction of the light iscontrolled. As a result, the liquid crystal panel arranged at the upperposition of the prism sheet 7 is irradiated uniformly by the lightradiated from the light guide plate 2. Thus, a display having a uniformluminance distribution can be obtained at the liquid crystal panel.

In this case, if consumption of electricity grows in a narrow spacewhere the cold cathode fluorescent tubes 3 a are arranged in order toproduce the high luminance of the liquid crystal display, other membersin the liquid crystal display apparatus are thermally influencedseriously. In addition, it is difficult to increase the number of thecold cathode fluorescent tubes 3 a in the narrow space. In a structurein which the number of the cold cathode fluorescent tubes 3 a can beincreased, an advantage of the edge light type back light unit, namely acapability of making the liquid crystal display apparatus thin, isobstructed.

FIG. 2 is a schematic illustration of a structure of the related artdirect under type back light unit.

Referring to FIG. 2, in the direct under type back light unit 1 b, theplural cold cathode fluorescent tubes 3 b extending to front and backdirections in a plane perpendicular to the paper of FIG. 2 are arrangedparallel in right and left directions. A lamp house 4 b is arranged on aperiphery of the line of the plural cold cathode fluorescent tubes 3 bas a reflector. A diffusion plate 6 b is arranged at an upper positionfrom the cold cathode fluorescent tubes 3 b, namely an irradiation sideof the cold cathode fluorescent tubes 3 b, for example at an upperposition of the lamp house 4 b. A frame part 8 of the direct under typeback light unit 1 b has a frame body configuration. The frame part 8includes a concave part 8 a and an opening part 8 b. The diffusion plate6 b is grasped between the concave part 8 a of the frame 8 and acircumference edge part of the lamp house 4 b. An edge part of the frame8 and a most external circumference edge part of the lamp house 4 b arefixed by a screw not shown in FIG. 2. A liquid crystal panel not shownin FIG. 2 is provided on an upper surface of the frame 8 with a spacer 9having a frame body configuration. The circumference edge part of theliquid crystal panel and the frame part 8 are covered with a frame bodynot shown in FIG. 2 such as a metal bezel except for a display surfaceof an upper side of the liquid crystal panel.

In a case of the direct under type back light unit, it is relativelyeasy and creates little problem to increase the electrical power orincrease the number of the cold cathode fluorescent tubes, as comparedwith the edge light type back light unit. Hence, it is easy for thedirect under type back light unit to produce a high luminance of theliquid crystal display.

However, in a case of the direct under type back light unit, there areserious problems with regard to an exchange of the cold cathodefluorescent tube and a dispersion of the luminance of the plural coldcathode fluorescent tubes, as compared with the edge light type backlight unit.

That is, in a case of the direct under type back light unit, when thecold cathode fluorescent tube is exchanged, it is necessary to removethe lamp house in which the plural cold cathode fluorescent tubes arearranged. Hence, it is complicated to exchange the cold cathodefluorescent tubes. Furthermore, in a state where the lamp house and theliquid crystal panel are separated, the diffusion plate is removed at aside where the lamp house is removed by removing the lamp house.Therefore, in this case, the liquid crystal panel faces outside air sothat an outside foreign body may adhere to the liquid crystal panel. Inaddition, as shown in FIG. 3, the spacer 9 of the liquid crystal displayapparatus assembled completely has a space shown by arrow a in FIG. 3 inorder to have measurement tolerances and efficiency in assembling theliquid crystal display apparatus. In this case, even if a space at theback light unit side is made small so that the foreign particle isprevented from invading, the particle may invade from the liquid crystalpanel side.

When a foreign body adheres to the liquid crystal panel, a problem suchas a defect of displaying regarding the liquid crystal panel occurs. Inorder to prevent the defect, there is an idea to exchange the coldcathode fluorescent tubes in a clean room. However, it is morecomplicated to exchange the cold cathode fluorescent tubes in a cleanroom.

In a case of not only the direct under type back light unit but also theedge light type back light unit, the back light unit is separated basedon the need for exchanging the lamps. The same problems in the directunder type back light may occur in the edge light type back light.

Furthermore, the direct under type back light has a structure in whichthe cold cathode fluorescent tubes are arranged in parallel. Each of thecold cathode fluorescent tubes irradiates only around the circumferencesof the each of the cold cathode fluorescent tubes. Hence, it isdifficult to maintain a uniform light level, as compared with the edgelight type. Accordingly, if the luminance is reduced due todeterioration of one of the cold cathode fluorescent tubes, the reducedluminance causes a non-uniform luminance distribution of the back lightunit and eventually of the liquid crystal panel. Therefore, when theconsumption of the electricity increases in order to realize highluminance, non-uniform luminance of the liquid crystal panel occursfrequently since the service life of the cold cathode fluorescent tubeis shortened.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providea novel and useful back light unit and a liquid crystal display in whichone or more of the problems described above are eliminated.

In addition, there are two more specific objects of the presentinvention. It is a first object of the present invention to provide aback light unit and the liquid crystal display apparatus wherein it ispossible to exchange the lamp easily without adhesion of foreign bodiesto the display part such as a liquid crystal panel. It is a secondobject of the present invention to provide a back light unit and aliquid crystal display apparatus wherein the luminance distribution isnot reduced in whole, even if one or more of the plural lamps aredeteriorated and the degrees of their luminance are reduced.

The above objects of the present invention are achieved by a back lightunit, including a lamp, a lamp house where the lamp is housed, adiffusion plate provided parallel to a main surface of the lamp house, adisplay part receiving light irradiated from the lamp and displaying, aframe member that has a structure in which the diffusion plate and thedisplay part can be housed inside of the frame member and thatdetachably connects to the lamp house, and a shield member connected ina range from the diffusion plate to the frame member so that a spacebetween the diffusion plate and the frame member is shielded.

According to the present invention as described above, foreign bodiesare prevented from invading from the space between the diffusion plateand the frame member and adhering to the display part, when the lamphouse is separated from the frame members and the lamps are exchanged.As a result, the defect of displaying regarding the liquid crystal panelis prevented from occurring when the lamps are exchanged. In addition,it is not necessary to exchange the lamps in a clean room and to handlethe lamps carefully.

In this case, when the shield member is an elastic body such as asilicon gum sheet and a resin sheet, the sealability between thediffusion plate and the frame member improves by putting the shieldmember between the diffusion plate and the frame member tightly. Theshield member and the diffusion plate and the frame member may beconnected with the adhesive material.

The diffusion plate may slide on the shield member.

According to the present invention as described above, when adeformation of the diffusion plate occurs due to heat or other causes,the deformation of the diffusion plate is absorbed by sliding thediffusion plate against the shield member so that a strain stress doesnot occur.

Another object of the present invention is to provide a back light unit,including a lamp, a lamp case wherein a plurality of the lamps being inclose formation are housed and that has a surface of an irradiation sidemade of a transparent material, a lamp house having a main surfacewherein the lamp case is detachably connected to an outside surface partsituated at a substantially center part of the main surface made of atransparent material, and a diffusion plate provided parallel to themain surface of the lamp house.

According to the present invention as described above, it is notnecessary to remove the lamp house when the lamp is exchanged. Rather,only the lamp case is removed. Hence, a seal structure of the liquidcrystal display apparatus may be maintained. As a result, it is possibleto prevent foreign bodies from invading at the time of exchanging thelamps, as improvement over the conventional art. In addition, it is easyto exchange the lamps. Furthermore, plural lamps being in closeformation form one light source so that there is no luminancedistribution even if the luminance of one or more of the lamps isreduced.

It is another object of the present invention to provide a back lightunit, including a lamp, a lamp case wherein a plurality of the lampsbeing in close formation are housed and that has a surface of anirradiation side made of a transparent material, a lamp house having aconcave part made of a transparent material and a main surface whereinthe concave part is situated at a substantially center part of the mainsurface and the lamp case is housed in the concave part, and a diffusionplate provided parallel to the main surface of the lamp house.

According to the present invention as described above, it is possible toshorten the height of the back light unit by the length of the lamphouse housed in the concave part without an outside connection to a mainsurface of the lamp house.

It is another object of the present invention to provide a liquidcrystal display apparatus, including a back light unit, and a liquidcrystal display mounted on the back light unit, the back light unitincluding a lamp, a lamp house where the lamp is housed, a diffusionplate provided parallel to a main surface of the lamp house, a displaypart receiving light irradiated from the lamp and displaying, a framemember that has a structure in which the diffusion plate and the displaypart can be housed inside of the frame member and that detachablyconnects to the lamp house, and a shield member connected in a rangefrom the diffusion plate to the frame member so that a space between thediffusion plate and the frame member is shielded.

According to the present invention as described above, it is possible toobtain a liquid crystal display apparatus in which the effect of theback light unit described above can be provided.

It is another object of the present invention to provide a liquidcrystal display apparatus, including a liquid crystal panel, a backlight unit provided on a back surface of the liquid crystal panel, and aspacer member provided at a space between the liquid crystal panel andthe frame member of the back light unit and having a frame configurationcomprised of four sides, wherein at least one side of the spacer memberincludes plural divisional parts and an end part of each of thedivisional parts comes in contact with an end part of another divisionalpart.

As described above, in the related art, the spacer member having a framebody configuration and formed between the liquid crystal panel and theframe member of the back light unit has a partially inevitable space.However, according to the present invention as described above, sincethe space is shielded, foreign bodies are prevented from invading fromthe space and adhering to the liquid crystal panel.

Other objects, features, and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a structure of a related art edgelight type back light unit;

FIG. 2 is a schematic illustration of a structure of a related artdirect under type back light unit;

FIG. 3 is a plan view of a spacer of the direct under type back lightunit shown in FIG. 2;

FIG. 4 is a schematic illustration of a structure of a back light unitof a first embodiment of the present invention;

FIG. 5 is a plan view of a spacer member of the back light unit shown inFIG. 4;

FIG. 6 is a partially enlarged view of another example of the back lightunit according to the first embodiment of the present invention;

FIG. 7 is a schematic illustration of a structure of a back light unitof a second embodiment of the present invention; and

FIG. 8 is a schematic illustration of a structure of a back light unitof a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given, with reference to the FIGS. 4 through8, of embodiments of the present invention.

FIG. 4 is a schematic illustration of a structure of a back light unitof a first embodiment of the present invention.

Referring to FIG. 4, a back light unit 10 of the first embodiment of thepresent invention is a direct under type back light unit.

In the back light unit 10, eight cold cathode fluorescent tubes (lamps)12 extending to a front and back directions in a plane perpendicular tothe paper of FIG. 4 are arranged parallel in right and left directions.The cold cathode fluorescent tubes 12 are housed in a lamp house 14 madeof aluminum material, for example. A reflection sheet 16 such as E60Lmade by TORAY Industries Inc. is applied on an inside surface of thelamp house 14 as a reflector.

At an upper position of an irradiation side of the cold cathodefluorescent tube 12, the diffusion plate 18 is provided parallel to themain surface 14 b of the lamp house 14. A frame member 20 having a framebody configuration is provided in order to support the liquid crystalpanel 26. An opening part 20 a is situated at the center of the framemember 20. The frame member is, for example, made of polycarbonate resinmaterial. The frame member 20 has a circumference projection part 20 bformed toward a side of the opening part 20 a. Because of this, theconvex parts 20 c and 20 d having notch configurations are formed onupper and lower parts of the circumference projection part 20 b in FIG.4. The circumference edge part of the diffusion plate 18 is inserted inthe concave part 20 d. A silicon gum sheet 22 such as a shield member oran elastic body is applied on a lower part in a range from the diffusionplate 18 to the frame member 20 as shown by an arrow A in FIG. 4, by anadhesion layer not shown in FIG. 4. As a result, a circumference edgepart of the diffusion plate 18 is united with the frame member 20.Because of this, a space formed between the diffusion plate 18 and theframe member 20 shown by an arrow B in FIG. 4 is shielded by the silicongum sheet 22. The frame member 20 is fixed at the circumference edgepart of the lamp house 14 by a fixing member such as a screw (notshown).

A spacer member 24 having a frame body configuration is provided on aconcave part 20 c of the frame member 20. An opening part 24 a issituated at a center of the spacer member 24. A liquid crystal panel(display part) 26 that receives light and displays is provided on thespacer member 24 so that the liquid crystal display apparatus can beobtained.

A frame body 30 such as a metal bezel covers the external circumferenceof the frame member 20 and fixes the circumference edge part of theliquid crystal panel 26 to the frame body 30. In this case, a spacebetween the frame body 30 and the circumference edge part of the liquidcrystal panel 26 is sealed by an elastic sheet, for example. As aresult, foreign bodies such as dust are prevented from invading into theinside of the liquid crystal panel 26 primarily.

Spacer member 24 will be described with reference to FIG. 5. FIG. 5 is aplan view of the spacer member 24 of the back light unit shown in FIG.4.

Referring to FIG. 5, the spacer member 24 has a frame configurationformed by four sides having approximately the same measurements.

Three of frame segments (side construction members) 32 a through 32 care prepared in order to construct three sides of the four-sided spacermember 24. Each frame segment 32 a through 32 c has substantially thesame length. Another frame segment 32 d having two divisional parts 32d-1 and 32 d-2 is prepared in order to construct the fourth side of thespacer member 24. The length where the divisional parts 32 d-1 and 32d-2 are connected is longer than the lengths of other sides (framesegments 32 a through 32 c). Notch parts 34 a and 34 b having stepconfigurations as connection parts are formed on side surfaces ofrespective end parts of the two of divisional parts 32 d-1 and 32 d-2.The notch parts 34 a and 34 b face each other. Adhesion is applied onone side surface of the end parts of the frame segments 32 a through 32d to fix these members. The remaining side may be divided into more thanthree parts. In this case, the notch parts having a step configurationas a connection part may be formed on both end parts of at least onedivisional part.

End parts of the three frame segments 32 a through 32 c come in contactso that the spacer member 24 has a rectangle configuration not havingone side. And then, one end part of the divisional part 32 d-1 comes incontact with an end part of the frame segment 32 a. One end part of thedivisional part 32 d-2 comes in contact with an end part of the framesegment 32 c. Furthermore, other end parts of two divisional parts 32d-1 and 32 d-2 come in contact with each other. In this case, the notchparts 34 a and 34 b come in contact with each other so that the endparts of the two divisional parts 32 d-1 and 32 d-2 are sealedcompletely. As a result, the inside and the outside of the spacer member24 are insulated from each other completely.

Because of this, it is possible in the present invention to prevent thepartially inevitable space formed at the connecting parts of the foursides of the spacer member 24 in the related art from forming. It ispossible to apply the above mentioned structure of the spacer member 24to not only the direct under type back light unit but also the edgelight type back light unit, and the edge light type back light unit alsocan obtain the same effect as the direct under type back light unit.

Since basic functions of the back light unit 10 and the liquid crystaldisplay apparatus 28 of the present invention are the same as in therelated art respectively, an explanation thereof will be omitted.

In the back light unit 10 and the liquid crystal display apparatus 28according to the first embodiment, a space formed between the diffusionplate and the frame member is sealed by the silicon gum sheet.Accordingly, when the lamp house is separated from the frame member andthe cold cathode fluorescent tube is exchanged, a foreign body isprevented from invading and adhering to the liquid crystal panel. Hence,a defect of displaying can be avoided. Therefore, it is not necessary toremove the lamp house in a clean room and to handle the lamps carefullyin order to prevent a foreign body from invading. If a foreign bodyinvades from the space formed between the diffusion plate and the framemember and the lamp house, the foreign body can be prevented fromadhering to the liquid crystal panel since the spacer member has acomplete seal structure.

FIG. 6 is a partially enlarged view of another example of the back lightunit according to the first embodiment of the present invention.Referring to FIG. 6, a circumference projection part 14 a projecting toan inside of the lamp house 14 may be provided at a circumference edgepart of the lamp house 14, so that the silicon gum sheet 22 may be putbetween the circumference projection part 14 a and the diffusion plate18 and the frame member 20. Because of this, it is possible to improvethe sealability between the diffusion plate 18 and the frame member 20.In this case, a tape made of resin such as polyethylene terephthalate(PET), polypropylene (PP), or polyethylene (PE) may be used instead ofthe silicon gum sheet 22.

In this case, if the adhesion layer is not provided on a part of thesilicon gum sheet 22 contacting the diffusion plate 18 and the diffusionplate 18 can slide against the silicon gum sheet 22, the deformation ofthe diffusion plate 18 due to heat or other causes is prevented bysliding the diffusion plate 18 against the silicon gum sheet 22. As aresult of this, a strain stress may be prevented.

Next, a description of a back light unit and a liquid crystal displayapparatus of a second embodiment of the present invention will be given,with reference to the FIG. 7. FIG. 7 is a schematic illustration of astructure of a back light unit of a second embodiment of the presentinvention.

Since basic structures of a back light unit 38 and a liquid crystaldisplay apparatus 40 are same as the back light unit 10 and the liquidcrystal display apparatus 28 respectively, parts in FIG. 7 that are thesame as the parts shown in FIG. 4 are given the same reference numerals,and explanation thereof will be omitted.

In the back light unit 38, plural cold cathode lamps 42 being in closeformation are provided at a substantially center part of a main surfaceof the lamp house 14.

In the back light unit 38 and the liquid crystal display apparatus 40according to the second embodiment of the present invention, the pluralcold cathode fluorescent tubes being in close formation form one lightsource. Accordingly, even if the luminance of one part of the coldcathode fluorescent tube is reduced, a non-uniform light radiated fromthe back light unit and a luminance distribution of the liquid crystalpanel are not caused. Accordingly, even if luminance of one part of thecold cathode fluorescent tube is reduced, it is not necessary toexchange the back light unit immediately. Hence, a number of exchangingthe back light unit decreases so that the foreign bodies have lesschance to invade the liquid crystal panel.

Next, a description of a back light unit and a liquid crystal displayapparatus of a third embodiment of the present invention will be given,with reference to the FIG. 8. FIG. 8 is a schematic illustration of astructure of a back light unit of the third embodiment of the presentinvention

Since basic structures of a back light unit 44 and a liquid crystaldisplay apparatus 46 are same as the back light unit 38 and the liquidcrystal display apparatus 40, respectively parts in FIG. 8 that are thesame as the parts shown in FIG. 7 are given the same reference numerals,and explanation thereof will be omitted.

In the back light unit 44, plural cold cathode fluorescent tubes 48 arehoused in the lamp case 50. The lamp case 50 extends to front and backdirections in a plane perpendicular to the paper of FIG. 8. The lampcase 50 has a configuration fitting a formation of the plural coldcathode fluorescent tubes 48 arranged as a circumferentialconfiguration. That is, the lamp case 50 long-extending to front andback directions in a plane perpendicular to the paper of FIG. 8 has across sectional configuration of a half of an ellipse. The lamp case 50is made of polycarbonate (PC) resin for example. The irradiationdirection of the cold cathode fluorescent tubes is made transparent. Thereflection sheet 16 as described above, for example, is applied on aback surface of the lamp house 50 as a reflector.

On the other hand, the concave part 52 a, long-extending to front andback directions in a plane perpendicular to the paper of FIG. 8 andhaving a configuration fitting to the lamp case 50, is formed at asubstantially center part of the main surface 52 b of the lamp house 52.A reflection sheet 16 is not applied on an inside wall part of theconcave part 52 a so that the inside wall part of the concave part 52 ais made transparent. Hence, the light from the cold cathode fluorescenttubes 48 permeates through the concave part 52 a.

The lamp case 50 where the cold cathode fluorescent tubes 48 are housedis connected to the concave part 52 a of the lamp house 52 detachably byproper fixing means. Because of this, the bottom surface 50 a of thelamp case 50 and the main surface 52 b of the lamp house 52 are the samesurface.

The back light unit 44 and the liquid crystal display apparatus 46according to the third embodiment of the present invention have the sameeffect as the effect obtained by the back light unit 38 and the liquidcrystal display apparatus 40 of the second embodiment of the presentinvention. In addition, when the cold cathode fluorescent tube isexchanged, it is not necessary to remove the lamp house. It is necessaryto remove just only the lamp case. Accordingly, it is possible toprevent a foreign body from invading when the cold cathode fluorescenttube is exchanged. In addition, it is possible to exchange the coldcathode fluorescent tube easily. Furthermore, the miniaturization of theliquid crystal apparatus is not obstructed by the lamp case.

The present invention is not limited to these embodiments, butvariations and modifications may be made without departing from thescope of the present invention. For instance, in the back light unit 44of the third embodiment of the present invention, it is not necessary toform the concave part in the main surface of the lamp house. Rather, alamp case having a rectangular parallelepiped configuration may beconnected from outside to the lower surface of the main surface of thelamp house for instance.

This patent application is based on Japanese priority patent applicationNo. 2001-360962 filed on Nov. 27, 2001, the entire contents of which arehereby incorporated by reference.

1. A back light unit, comprising: a plurality of fluorescent lamps; alamp house where the plurality of lamps are housed; a diffusion plateprovided parallel to a main surface of the lamp house; a frame member inwhich the display part and the diffusion plate can be housed and thatdetachably connects to the lamp house; a shield member shielding a spacebetween the diffusion plate and the frame member, the frame memberconnecting to the shield member, and the diffusion plate capable ofengagement with the shield member; and a lamp case in which theplurality of the fluorescent lamps are provided in close formation,wherein the lamp case is located at a substantially center part of themain surface of the lamp house, the lamps being arranged as acircumferential configuration within the lamp case, and the lamp casehaving a cross sectional configuration of a half of an ellipse.
 2. Theback light unit of claim 1, wherein each of the plurality of lamps is acold cathode fluorescent tube.
 3. The back light unit of claim 1,wherein in the event that one part of the plurality of lamps arereduced, a uniformity of light radiated from the back light unit ispreserved.
 4. The back light unit of claim 2, wherein in the event thatone part of the plurality of cold cathode fluorescent tubes are reduced,a uniformity of luminance radiated from the back light unit ispreserved.
 5. The backlight unit of claim 2, wherein in the event thatone part of the plurality of cold cathode fluorescent tubes are reduced,sufficient light is produced such that it is not necessary toimmediately exchange the back light unit.
 6. The back light unit ofclaim 1, wherein the lamp case is made of polycarbonate (PC) resin. 7.The back light unit of claim 1, wherein the lamp case is connected to aconcave part of the lamp house detachably by a fixing means.
 8. The backlight unit of claim 7, wherein a bottom surface of the lamp case and amain surface of the lamp house are the same surface.
 9. The back lightunit of claim 2, wherein when the cold cathode fluorescent tube isexchanged, it is not necessary to remove the lamp house, only the lampcase.
 10. The back light unit of claim 1, wherein the miniaturization ofthe liquid crystal apparatus is not obstructed by the lamp case.